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Verification method for level number selection based on mmc flexible direct current transmission system

A power transmission system, flexible direct current technology, applied in the direction of measuring electricity, measuring electrical variables, measuring devices, etc.

Active Publication Date: 2016-02-03
CHINA ENERGY ENG GRP GUANGDONG ELECTRIC POWER DESIGN INST CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, there is no complete level number selection verification method for MMC-based flexible DC transmission systems

Method used

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  • Verification method for level number selection based on mmc flexible direct current transmission system
  • Verification method for level number selection based on mmc flexible direct current transmission system
  • Verification method for level number selection based on mmc flexible direct current transmission system

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specific Embodiment 1

[0030] Figure 1-Figure 7 It constitutes the specific embodiment 1 of the present invention.

[0031] Embodiment 1 of the present invention relates to a filter selection and design method of an MMC-based flexible direct current transmission system, which is characterized by including the following steps:

[0032] 1) First, build a flexible DC transmission system simulation model based on the equivalent model when the three-phase voltage is symmetrical when the flexible DC transmission system is connected to the grid, and then add the NLM control algorithm model according to the built flexible DC transmission system simulation model, and the composition is based on the optimal The level approaching NLM method builds a simulation model for harmonic analysis of flexible HVDC transmission based on MMC, and forms a PSCAD simulation platform for flexible HVDC transmission system;

[0033] 2) According to the built flexible DC transmission system simulation model, input several sets of val...

specific Embodiment

[0054] The main feature of other specific embodiments of the present invention is that the value of the modulation ratio M input in step 2) is 0.6, 0.7, 0.8, 0.9, or 1. The rest is the same as in Example 1.

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Abstract

The invention discloses a level number selecting and verifying method based on a flexible direct-current transmission system of an MMC (Modular Multilevel Converter). The level number selecting and verifying method is characterized by comprising the following steps of: 1) establishing a simulation model of the flexible direct-current transmission system by an equivalent model when a three-phase voltage is symmetrical according to the flexible direct-current transmission system in a grid-connected operation process, so as to form a simulation model of flexible direct-current transmission harmonic analysis based on the MMC, which is established according to an optical level approaching NLM (Network Link Module) method, and form a PSCAD (Power System Computer Aided Design) simulation platform of the flexible direct-current transmission system; 2) inputting a plurality of groups of numerical values with a modulation ratio M so as to obtain various main parameters through the PSCAD simulation platform; and 3) describing a curve of changing each order of characteristic harmonic content of the NLM with a level number and a curve of changing a THD (Total Harmonic Distortion) content with the level number through the PSCAD simulation platform, combining voltage class verification to obtain the feasibility and accuracy of a cascade unit number, and obtaining the level number corresponding to a critical point meeting a harmonic requirement simultaneously. By utilizing the level number selecting and verifying method provided by the invention, the accuracy and reasonability of selection of the level number and the corresponding cascade unit number of the flexible direct-current transmission system of the MMC can be verified through the simulation platform and a calculation procedure.

Description

Technical field [0001] The invention relates to a design method of a flexible direct current transmission system, in particular to a method for selecting and verifying the level number of a flexible direct current transmission system based on MMC. It belongs to the field of power transmission and distribution technology. Background technique [0002] With the development of high-voltage and high-power fully-controlled power electronic devices (IGBT, IGCT), flexible DC transmission technology is widely used in the field of power transmission and distribution. It is the most representative technology in the field of smart grids and has engineering applications at home and abroad. more and more. Compared with conventional DC transmission technology, this technology has good control performance and is the latest generation of DC transmission technology, but the converter loss is much higher than that of conventional DC transmission. This technology has been developed abroad for more...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/00
Inventor 彭冠炎余梦泽简翔浩谭茂强伍广俭朱海华张劲松陈冰
Owner CHINA ENERGY ENG GRP GUANGDONG ELECTRIC POWER DESIGN INST CO LTD